Conversion of hydrocarbons



Feb. 25, 1936. J, P. DAUGHERTY, JR

CONVERSION OF HYDROGARBONS Filed Feb. 1o, 193s ATTORNEY Patented Feb. 25, 1936 UNITED vSTATES PATENT oFFicE CONVERSION F HYDROCARBONS Application February 10, 1933, Serial No. 656,064

6 Claims.

"'\ This invention relates to the P1'0dutin of low' er boiling hydrocarbons such as benzine, gasoline, naphtha, kerosene and the like from high boiling distillates such as result from the distillation of crude petroleum and oils made by the destructive distillation of carbonaceous material.

Pyrolytic cracking or transforming of hydrocarbons is well known and various systems lo differing from one another only in minor details are in common use. A more recent development involves the catalytic conversion of hydrocarbons by a continuous process utilizing.two or more converters containing catalytic material l which is regenerated or reactivated in situ so that each converter may be alternately on stream and in regeneration, as indicated, for example in the copending application of Eugene J. Houdry, Serial No. 610,567, led May l1, 1932. In the pyrolytic systems, .it is common practice to eect continuous recycling of the residues from the fractionating column under the same temperature and pressure conditions, while in the aforementioned catalytic process the residues are segregated to provide separate and distinct passes at atmospheric or low pressures and at increasing temperatures in the later passes. The pyrolytic systems produce usually, from a fresh feed, a gasoline of rather low octane rating, as compared with the catalytic process, but appear to 4handle the more refractory residues with reasonable facility. On the other hand, the catalytic process makes its best yield in the early passes and produces a product which is more easily refined and stabilized than that resulting from the pyrolytic systems.

One object of the invention is tocombine the pyrolytic`and catalytic processes in such a way as to secure certain advantages of both while avoiding certain of their disadvantages. Other objects will be apparent from the detailed description which follows.

One concrete embodiment of the invention is illustrated diagrammatically in the single figure 45, of the accompanying dra-wing- The apparatus as .disclosed combines a catalytic system. indicated generally by reference character A, with a pyrolytic system, indicated by B, to produce a high yield of low boiling hydrocarbons, such as gasoline, having a good antiknock rating. The catalytic system conforms in general to that disclosed in the aforesaid copending Houdry application, Serial No. 610,567. It comprises a tubular heater l a and two or more catalytic converters 2a containing catalytic material capable of making the desired conversion, such as a contact mass consisting of an activated hydrosilicate oi aluminum with or without the addition of active metal oxides preferably in molded form, as disclosed, for example, in the 5 copending application of Eugene J. Houdry, Serial No. 600,581, filed March 23, 1932, so as to be capable of regeneration in situ. 'I'he catalytic converters are arranged for alternate operation on streami and in regeneration, the vaporlzed l0 products from' heater la being fed thereto through valved line 3a at atmospheric pressure or low superatmospheric pressure and at a temperature of from 750 to 1000 F, while the converted products are discharged througlrvalved l5 line la. The regenerating medium, which may be an oxidizingl agent, such as air diluted, if desired, with steam or flue gas, may be admitted through a valved connection 5a and the fumes carried away by connection 6a. n A

The pyrolytic system may be of any known or suitable type, either liquid or vapor phase, such as Dubbs, Cross, tube and tank, the Florez, etc., the one indicated comprising a tubular heater Ib and a reaction or evaporating chamber 2b. 'Ihe hydrocarbon vapors from heater Ib are fed to chamber 2b by a. line 3b, under substantial pressure and at a temperature ranging from 850 to l F., and the converted products are discharged through a line 4b. Tarry residues may be drawn from the -Abottonr of reaction chamber 2b through a valved line 5b.

Each system has its own fractionating column, y line la from catalytic system A discharging into 35 fractionator 1a, while line Ib from pyrolytic system B discharges into fractionator 1b. Trimmingcoils 8a and 8b may be provided in the tops of each of the fractionating columns, if desired, to control the temperatures thereof. The vapors issue from the fractionators through lines 9a and 9 respectively, to be condensed, refined and/stabilized, eithenseparately or together, afi/may be desired, by other apparatus which is not disclosed since it forms no part of the present invention.

The fresh feed, such as a gas oll, is fed by line l0v direct or optionally through a heating coil Il in the top of fractionator 1a, to heat exchangers Iza and |2b in vapor lines la and 4b, respectively, leading from the two converting systems, and is discharged in a preheated condition into an accumulator tank I3. -A line Il is provided -for pumping material from the bottomof the the pyrolytic system is recycle stock which is pumped through line I 5 from the bottom of fractionator 1b. A connection I6 from the bottom of fractionator Ia permits recycle stock from the bottom of the latter to be pumped optionally or in any desired proportion through a valved branch I'I either into accumulator tank I3, or by valved branch I8 into fractionator 1b. Tank I3 may be vented to either of the fractionating columns, as desired. The line I9 indicates such a connection to fractionator 1a.

By a proper proportioning ofthe two systems, and by pumping the bulk of the recycle stock from fractionator 'Ia to fractionator 1b, the composition of the material fed from tank I3 to heater Ia of the catalytic system may be kept close to fresh feed or gas oil, so as to secure the high yield and high octane characteristics of the early passes in the catalytic process, while the recycling stock is handled, to a large extent, if not exclusively, by the pyrolytic system. In this way, existing pyrolytic plants may be combined with continuously operating catalytic plants which supply to them a cracking stock from which they can produce a gasoline of 4high octane number. 'I'he products from both systems may be treated individually or blended to facilitate the stabilizing of the same.

I claim as my invention:

1. In apparatus for the conversion of higher boiling hydrocarbons into lower 4boiling hydrocarbons, in combination, a catalytic system comprising means for heating hydrocarbons in a stream and at least two 'converters connected thereto for operation alternately on stream and in regeneration and containing catalytic material capable of making the desired conversion and of regeneration in situ, a pyrolytic system comprising means for heating hydrocarbons and a chamber connected thereto, a fractionating column connected to said catalytic system to receive the products therefrom, a second fractionating column connected to said pyrolytic system to receive the products therefrom, means for passing fresh feed into heat exchange with the products of both said systems and thence to said heating means of said catalytic system, means for sending the bottoms from said second fractionating column to said heating means of said pyrolytic system, and means including connections and controls for selectively mingling bottoms from said first fractionating column with saidfresh feed and with the contents of said second fractionating column.

2. In apparatus for the conversion of higher boiling hydrocarbons into lower boiling hydrocarbons,' in combination, a catalytic system comprising means for heating hydrocarbons in a stream and at least two converters connected thereto for operation alternately on stream and in regeneration and containing catalytic material capable of making the desired conversion and of regeneration in situ, a pyrolytic system comprising means Afor heating hydrocarbons and a chamber connected thereto, 4a fractionating column connected to said catalytic system to receive the products thereof, a second fractionating column connected to said pyrolytic-.system to receive the products thereof, means for directing fresh feed to the heating means of said catalytic system, means to add bottoms from said rst fractionating column to said fresh feed, means to discharge bottoms from said Yfirst fractionat: ing column into said second fractionating column, and means for conducting bottoms from said second fractionator to the heating means of said pyrolytic system.

3. In apparatus for the conversion of higher boiling hydrocarbons into lower boiling hydrocarbons, in combination, a catalytic system comprising means for heating hydrocarbons in a stream and at least two converters connected thereto for operation alternately on stream and in regeneration and containing catalytic material capable of making the desired conversion and of regeneration in situ, a pyrolytic system comprising means for heating hydrocarbons and a chamber connected thereto, a fractionating column connected to said catalytic system to receive the products thereof, a second fractionating column connected to said pyrolytic system to receive the products thereof, an accumulator tank, heat exchangers in the connections to both said fractionators, means sending fresh feed through said exchangers and thence into said tank, means for discharging recycle stock from the bottom of said first fractionator at will and in any desired proportion into said tank and into said second fractionator, a connection from said tank to the heating means of said catalytic system, and a connection from the bottom of said lsecond fractionator to the heating means of said pyrolytic system.' i

4. In apparatus for the conversion of higher boiling hydrocarbons into lower boiling hydrocarbons, in combination, a catalytic system comprising means for heating hydrocarbons in a stream and at least two converters connected thereto for operation alternately on stream and in regeneration and containing catalytic material capable of making the desired ,conversion and of regeneration in situ, a pyrolytic system comprising means for heating hydrocarbons and a chamber connected thereto, a fractionating column connected to said catalytic system, a second fractionating column connected to said pyrolytic system, an accumulator tank into which preheated fresh feed is discharged, valved connections from the bottom of said first fractionator to said tank and to said second fractionator, a vent connection from said tank, a feed connection from said tank to the heating means of said catalytic system, and a feed connection from the bottom of said second fractionator to the heating means of said pyrolytic system. L

5. In apparatus for the conversion of higher boiling hydrocarbons into lower boiling hydrocarbons, in combinationa catalytic system comprising means for heating hydrocarbons in a stream and at least two converters connected thereto for operation alternately on stream and in regeneration and containing catalytic material capable of making the desired conversion and of regeneration in situ, a pyrolytic system comprising means for heating hydrocarbons and a chamber connected thereto, a fractionating column connected to said catalytic system, a second fractionating column connected to said pyrolytic system, an accumulator tank into which preheated fresh feed is discharged, means for discharging bottoms from said rst fractionator atvwill either into said tank or into said second fractionator, means for `feeding material from said tank to the heating means of said catalytic system, means for feeding material from the bottom of said second fractionator to the heating means of said pyrolytic system, and a vent connection from said tank into said rst fractionator.

6. Process of converting higher boiling hydrocarbons into lower boiling hydrocarbons which comprises passing the starting material through a vaporizing zone and then at low pressure into a converting zone containing catalytic material having selective adsorptive properties maintained in the temperature range of 750 to 1000 F., discharging the vapors into a vapor fractionating zone where-partial condensation occurs, withdrawing the heavy condensate from the bottom of the fractionating zone, mixing a part of the heavy condensate with preheated fresh feed to form the starting material for said vaporizing zone and then passing the mixture to said vaporizing zone, introducing the remainder of the heavy condensate into the lower portion of a second vapor fractionating zone, withdrawing heavy condensate from the bottom of said second fractionating zone, sending said last named condensate through a cracking zone and then at relatively high pressure into a pyrolytic reaction zone maintained in the temperature range of 850 to l100 F., discharging the vapors from said last named reaction zone into said second fractonating zone, and withdrawing the overhead vapors from both said fractionating zones to provide the desired lower boiling hydrocarbons.

JAMES P. DAUGHERTY, JR. 

